free rotating wheels?

Has anyone toyed with the idea of making a unicycle like a bike in
asence that you can pedal forwards and when you stop pedaling you just
coast and can't really ride backwards?

I mean.. obviously you would have to mount a brake on it, but i was
wondering ifthe theory has been tested.....


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Yes it has...by Joe maybe?

P.S. How long is that animation going to stay in your signature line?



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Really? I would desprately like to see a vid. of it ridden. PLus, how
hard would it be? It just seems like a really practical idea for
commuting.

As long as it takes, andrew. As long as it takes.


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On the video I saw the person who I think was Joe got 5m or so but then
stopped pedaling (for fun I assum) and did a pretty fun looking
dismount.

P.S. Oh God, they're multiplying!


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XWonka, isn't what you're describing essentially what bicyclists do when
they do wheelies? Just get rid of the front half of the bike, and there
you go.


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XWonka wrote:

Has anyone toyed with the idea of making a unicycle like a bike in
that you can pedal forwards and when you stop pedaling you just
coast and can't really ride backwards?

I built a forward only drive unicycle in 1991 that coasts when pedaling
is stopped and backward pedaling has no effect.

The hub consists of a 5/8" axle, a regular bearing and a unidirectional
bearing with a hub shell that fits snuggly over the two bearings. The
axle can move freely in one direction relative to the hub shell and the
axle and hub shell must move as a fixed unit in the other direction due
to the unidirectional bearing. The hub assembly is mounted to any
standard unicycle frame via the two normal bearings in the frame. Thus
such a forward only drive unicycle has a total of four bearings.

The hub assembly bearings have an inside diameter of 5/8" and the
outside diameter was 1". The hub shell is a 1" inside diameter pipe
with flanges welded to each end.

Tom Miller of The Unicycle Factory helped me build the hub assembly.

WARNING: The unidirectional bearings wear out fast and the bearings
must fit quite snug. I used three unidirectional bearings in the course
of a year of moderate use. Should be used only in level areas to reduce
stress to the unidirection bearing. Try to minimize applied torque
while riding to prolong unidirectional bearing life.

In a previous post, Ken Fuchs wrote:

It used a special needle bearing. The bearing would allow the axel to
rotate in one direction (free wheel), but not the other direction.
The needle bearings can move slightly in the direction of axel
movement in depressions that are normal depth on one side (i.e. the
clockwise side) and shallow depth on the other side (i.e. the
counter-clockwise side). Each bearing turns freely on the deep side
of its depression and binds tightly against the axle on the shallow
side of its depression. Thus the axle turns freely in the clockwise
direction (freewheels) and binds to the bearing after a few degrees
axel movement in the counter-clockwise direction.

Instead of a normal hub, the unidirectional unicycle has a hub shell,
axel, a normal bearing on one side and a unidirectional bearing on the
other side. These two bearings are press fitted into each side of the
hub shell and the axel is placed inside these bearings. This hub
assembly is attached to a standard unicycle frame via two normal
unicycle bearings just like a normal hub would.

The unidirectional (clutch) bearing failed after at least two
months of daily use of 1-2 hours each day. I bought some spares and
later reversed the direction of the seat, making it a backward-only drive
unicycle. It was originally a forward-only drive unicycle.

I don't think the unidirectional bearing was up to the stress of
human powered crank torque. Also, the press fit seemed to get looser
after thousands of clutch uses (every time pedaling was engaged), and I
switched the clutch bearing to the other side of the hub shell.
(Alternatively, the inside of the hub shell actually may have been
machined down too much on one end when originally made.) A
unidirectional bearing on each side might deal with the stress much
better. Or beefer clutch bearings, if they exist and are reasonably
priced. The ones I have were a little more than $10 each.

Maybe using two clutch bearings instead of one clutch bearing and one
regular bearing would be sufficient to handle the forces involved.

In another previous post, Ken Fuchs wrote:

The inside diameter of the hub shell was probably increased after
months of braking action on that surface. It probably should have
been a tighter press fit. Switching the clutch bearing to the other
side helped some.

Also, it is probably true that the clutch needle bearing used was not
designed to handle the torque generated by human legs. I tried to
baby it, but the first one still eventually failed. However, the
replacement bearing never failed, probably due to my increased
experience on the cycle and the continued avoidance of over-stressing
the clutch bearing.

In yet another previous post, Ken Fuchs wrote:

Tom Miller build a custom coasting hub using a clutch bearing, but it
had no brake. Tom and I built a second such hub in 1991 which I used
to learn coasting forward and then backwards and still have today.
I'd coast on this cycle until I fell and if I ran the velocity down to
near zero, I'd just start pedaling a bit and coast a few more meters,
etc. At that time, unicycles didn't have brakes other than the fixed
wheel crank set itself and I didn't need one for my purpose of
learning to coast on the freewheeling hub, so I never considered ever
adding one. The rsu archives contain more info on this particular hub
(and the corresponding coasting machine).

It would be interesting to hear of any bicycling or tricycling hubs
that could be readily adapted for a coasting unicycle. Maybe the
brake can be utilized to learn coasting faster? Maybe the brake can
be adjusted so it slows down the coasting machine, but doesn't lock
the wheel?

Good luck to any coasting machine builders out there in uni-land!

In a previous post, john_childs wrote:

Power Cranks http://www.powercranks.com/ use clutch bearings (one
clutch bearing on each crank). These are weird cranks that only apply
power when you pedal forward. The clutch bearings they use are able
to handle the power output of professional road cyclists without
slipping. The bearings were rather large which explains the somewhat
bulky design of the cranks.

Perhaps you need to use larger clutch bearings. Or the hub body may
need to be made out of a harder material.

With the right bearings and the right hub body this is probably the
easiest way to make a freewheel unicycle hub.

XWonka wrote:

I mean.. obviously you would have to mount a brake on it, but i was
wondering if the theory has been tested.....

The coasting machine works OK without a brake, assuming the goal is to
coast indefinitely (occasionally pedaling to maintain forward movement)
without one's feet leaving the pedals. Surely a brake could be added to
assist in regaining balance from a backward lean (too great for coasting
reflexes to compensate or if coasting is not even a goal). Such a
coasting machine would be like a unibike without gears and in a standard
unicycle like (pedals and wheel share the same center point) design.

Sincerely,

Ken Fuchs

XWonka wrote:

Really? I would desperately like to see a video of it ridden. Plus,
how hard would it be? It just seems like a really practical idea for
commuting.

A forward only drive standard unicycle with a brake would probably be no
harder to ride than a unibike and maybe easier due to the simpler weight
distribution. The coasting part would still be very hard though,
assuming one wants to coast, since coasting is not required with the
addition of a brake.

Sincerely,

Ken Fuchs

nosabe332 wrote:

would it be possible to make a free wheel that could lock in by means
of electronics? i'm thinking that it would be highly unfeasible and
ridiculously impractical, but so was the computer at its inception.

Yes it would be but it would require quite a much room because the
locking with electrics would require quite a much power to work fast
enough.


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"joona" wrote in message
...

nosabe332 wrote:

would it be possible to make a free wheel that could lock in by means
of electronics? i'm thinking that it would be highly unfeasible and
ridiculously impractical, but so was the computer at its inception.

Yes it would be but it would require quite a much room because the
locking with electrics would require quite a much power to work fast
enough.

I used to work with big high speed line printers, that had a magnetic
clutch/ brake assemble, activated by (I think) 12 volts DC. I have
occasionally wondered whether these things might have a uni application,
they worked very quickly, and we used them in a stop start mode with about
20 cycles per second. The 12 volts were applied hard on, but with a lower
voltage I guess the magnetic dust in these things might cloy more gradually.
Don't know how easy they would be to install, if they even proved to be
suitable version available. One for the mechanics amongst us maybe?

The magnetic devices or motors won't necessarily take too much room.
It's the battery that causes problems. It might take quite a big current
to make them work. I suppose those
magnetic brakes didn't work with batteries.


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